Chemical production facilities for dealing with liquid chemical products such as acrylic acid, include various handling devices such as reactors, distillation columns, storage tanks and other equipments fitted thereto such as pumps (refer to Japanese Patent Application Laid-open (KOKAI) No. 2003-146936). In the chemical production facilities, the liquid chemical products have been sampled from the respective handling devices during operation thereof, and subjected to inspection and analysis to check results of reaction in the operating reactors as well as qualities of distillates and bottom liquids obtained from the distillation columns. Also, in the case where the chemical production facilities are stopped for inspection and repair thereof, the chemical products are discharged from the respective devices into containers, etc., by means of a pump. In particular, if (meth)acrolein, (meth)acrylic acid, (meth)acrylic acid esters, etc., remain even in a very small amount in the handling devices or conduits, these substances tends to be polymerized and form solids therein, resulting in clogging of the devices or conduits. Therefore, these substances must be surely removed from the handling devices or conduits after stopping the operation of the facilities.